Method of making fibers



March 13, 1951 B. MONTERO METHOD OF MAKING FIBERS Filed April 21, 1947 fMM Ew m O m R 0 5 T M M W H W H w HA RR/s, K/ECH, F0$TR a HARE/5" by Patented Mar. 13,1951

UNITED STATES PATENT OFFICE 8 Claims.

My invention relates in general to the manufacture of filaments or fibers and, more specifically, to a method of making fibers which are particularly designed. for use in manufacturing ordinary brooms, whisk brooms, etc., a primary object of the invention. being to provide an artificial fiber having a straw-like appearance simulating that of the fibers commonly used in such brooms.

Artificial fibers or bristles for articles of this nature have been made from various of the socalled plastic materials, such as polystyrene, cellulose plastics, vinyl resins, etc., by extrusion through suitable orifices, but such fibers have been. subject to two principal disadvantages. The first of these resides in the fact that materials of the foregoing nature, and particularly polystyrene, tend to become so brittle during extrusion that they are unsatisfactory for use as broom straws. portant, disadvantage of artificial fibers produced by extruding such materials is that the resulting fibers are smooth and uniform and have an artificial appearance which is extremely unlike that of ordinary broom straws. This smooth, artificial appearance has been found to persist even when the materials are extruded through irregularly shaped orifices, although to a somewhat lesser extent.

As a result of the artificial appearance of brooms made of extruded fibers, such brooms have not been received very favorably by the general public. My method, however, provides artificial fibers for use in brooms which have such a natural appearance that the artificiality thereof cannot be detected except, perhaps, upon close inspection.

I have found that artificial fibers having the desired characteristics may be manufactured from various of the so-called plastic materials, such as polystyrene for example, by drawing a filament from a body of the material in its plastic state, which is an important object of m invention. Drawing the material in this manner results in an irregular filament which maybe severed into suitable lengths to form fibers having a straw-like appearance very similar to that of ordinary broom straws. Moreover, drawing such materials as polystyrene produces fibers having greater flexibility than comparable extruded fibers, which is an important feature of the invention.

More specifically, it is an object of my invention to provide a method which involves maintaining a substantially cone-shaped body of the The second, and perhaps the most immaterial in its plastic state and continuously drawing. a filament from the apex of the cone. Another object inv this connection is to provide a method whereinthe Volume of the cone is maintained substantially constant by adding material in its plastic state to the cone through a relatively large orifice at a. rate substantially equal to the rate at which the material is drawn from the apex of the cone.

A further object of the invention is to provide a filament which is flattened somewhat so that it is generally oblong or elliptical in cross section to enhance its natural appearance. In connection with one embodiment of my invention, it is an object to flatten the filament by drawing it at an angle with respect to the axis of the orifice through which the material in its plastic state is fed so that the axis of the cone produced at the outlet end of the orifice makes an angle of less than with respect to the base of the cone. A further object in this connection is to provide a method of flattening the filament which includes bending and subsequently straightening the filament, as by passing it over a roller, for example, while the material of which. the filament is formed is still in at least a semi-plastic state.

An additional object of the invention is to provide a method whereb the thickness of th filament may be varied by varying the rate at which the filament is drawn and/or by varying the plasticity of the material fed through the orifice.

The foregoing objects and advantages of my invention, together with various other objects and advantages thereof which will be evident hereinafter, may be realized through the employment of the exemplary embodiment illustrated in the accompanying drawing and described in detail hereinafter. Referring to the drawing:-

Fig. l is a semi-diagrammatic view of one form of apparatus which is capable of performing the steps of the method of my invention;

Fig. 2 is a semi-digrammatic view of another form of apparatus which is suitable for use in connection with my method.

Fig. 3 is a view illustratin 'an artificial fiber produced by my method; and

Figs. 4 and 5 are views showing possible cross sectional shapes for the artificial fiber illustrated in Fig. 3.

Referring particularly to Fig. 1 of the drawing, I show a receptacle H3, preferably a cylinder, for the material which is to be formed into fibers or filaments. In order to maintain the material ll ina plastic state, I prefer to provide means I2 for heating the material, the heating means being rial may be expelled from the cylinder, as by a piston 8. The pressure applied to the mate- U rial U need be sufiicient only to causethematerial to flow slowly through the orifice I? and, as the plasticity of the material increases, the pressure applied thereto may be correspondingly decreased. In instances wherein the material H is heated to such a temperature that its viscosity is relatively low, the weight of the piston is may be sufiicicnt to produce the desired rate of flow, and, at higher temperatures, the material may even be sufiiciently plastic to fiow through the orifice if or" its own accord without the application of any external pressure.

The material fed through the orifice ll forms a globule which is maintained substantially in the shape of a cone l9 by continuously drawing a filament 2c of the material from the apex of the cone by means of counter-rotating rollers 2|, for example. It will be understood that the rate at which the material Ii in its plastic state is fed through the orifice H and the rate at which it is drawn from the cone t9 must be maintained substantially constant so that the volume of the cone will remain substantially constant. If, for example, the rate of speed exceeds the drawing rate, the cone is will become enlarged and will tend to sag under its own weight, since the material forming it is in a plastic state, so that the cone or the filament 28 will break. Similarly, if the drawing rate exceeds the rate at which the material H is fed through the orifice II, the volume of the cone will gradually decrease and rupture of the filament will result. Moreover, the drawing and feeding rates must be compatible with the plasticity of the material H as will be discussed in more detail hereinafter.

It will be understood that the drawing rollers 21 should be located a sufiicient distance from the orifice ll so that the material forming the filament 26 will have set sufficiently to prevent transformation thereof into a sheet by the drawin rollers. After the filament 2!] passes between the drawing rollers 2i, it may be wound on a reel 24, as shown in Fig. 1, or, preferably, may be severed into suitable lengths, as indicated in Fig. 2, by any appropriate means to form fibers or bristles which may subsequently be used in the manufacture of brooms, for example. It will be understood that if the filament 26 is wound on the reel 24 as shown in Fig. l, the reel must be located at such a distance from the orifice I! that the filament 26 will have cooled substantially to the ambient temperature so that a permanent set will not be imparted to the filament when it is wound on the reel.

I have found that the fibers 25 formed by drawing the filament 26 from the cone H) in the foregoing manner have an irregular surface which produces an appearance closely resembling that of the natural fibers ordinarily used in brooms,

or the like. As best shown in Fig. 3, the drawing operation does not produce a rod of uniform thickness throughout its length, the resulting filament 20, and the fibers 25 produced by severing the filament, having bumps or projections 28 thereon which avoid the artificial appearance resulting from extrusion. Moreover, when polystyrene in particular is employed for the material I forming the filament 20, I have found that the resulting filament is far more flexible than similar filaments produced by extruding the polystyrene. Although I do not wish to be limited to my theory on this point, I believe that drawing the filament 29 in the manner described produces a molecular orientation which differs from that resulting from extrusion and which makes the filament less brittle.

I have found that an even more natural appearance may be obtained by flattening the filament 2!) somewhat during the drawing operation so as to produce an oblong or elliptical cross sec-- tion as indicated in Figs. 4 and 5. Without such a flattening operation, the filament 20 tends to have a generally circular cross section due to the action of the surface tension of the material when the filament is first formed at the apex of the cone l9 while the material is still in a plastic state. In other words, the drawing operation per se produces a filament 20 which is of a generally circular cross section, but which has an irregular surface and which is of nonuniform diameter throughout its length.

The filament 20 may be flattened in various ways, one of which is indicated in Fig. 1. I have found that by drawing the filament 20 at an angle with respect to the axis AA of the orifice H, a flattened filament of generally elliptical cross section results. It will be noted that drawing the filament 20 at an angle with respect to the axis of the orifice ll produces a cone l9 whose axis intersects its base at an angle of less than thereby producing a cone with a surface having portions 2'1 and 28 of different lengths, The flattening of the filament 20 which results from drawing it in this manner probably is due to differential cooling of the portions 21 and 28 of the surface of the cone 19. It will be apparent that since the portion 21 of the conical surface is longer than the portion 28 thereof, the material forming the portion 21 will be less plastic by the time it reaches the apex of the cone than the material forming the portion 28 because of the fact that the material forming the longer portion 2i is exposed to the ambient air for a greater length of time. Consequently, distortion of the filament 20 occurs as it is formed at the apex of the cone I9 and such distortion results in a generally elliptical cross sectional configuration as indicated in Fig. 4.

Although the degree to which the filament 2B is flattened during the drawing operation may be varied by varying the angle of inclination of the axis of the cone [9 with respect to the axis AA of the orifice i1, I have found that when the filament 2B is to be severed into fibers 25 for use in the manufacture of brooms, or the like, the filament is preferably drawn in such a direction that the axis of the cone is inclined with respect to the base of the cone at an angle of approximately 45. It will be understood, of course, that the direction in which the filament 20 is drawn substantially coincides with the axis of the cone.

As shown in Fig. 2 of the drawing, the filament 26 may be flattened by bending it, as by passing it over a roller 29 for example, while the material forming the filament is still in at least a semiplastic state, i. e., before the material forming 5, the filament has set completely. Training the filament over the roller 29 in this manner tends to produce an oblong cross sectional configurae tion such as that shown in Fig. 5, whereas drawing' the filament at an angle with respect to the base of the cone It as previously discussed tends to produce a more nearly elliptical cross sectional configuration as indicated in Fig. 4. It will be noted that when the filament 20 is flattened by curving and subsequently straightening it in the manner shown in Fig. 2, the filament may be drawn from the apex of the cone [9 in a direction coinciding with the axis A-A of the, orifice I? so that the axis of the cone is perpendicular to the base thereof.

The method of my invention thus results in a filament 20 which has an irregular surface and which is of non-uniform thickness both transversely and throughout its length so that the fibers 25' which may be produced by serving the filament periodically have a natural appearance simulating that of the fibers ordinarily used in the manufacture of brooms and similar articles. Thus, my invention may be utilized to manufacture fibers for brooms which cannot readily be distinguished from the brooms heretofore manufactured from natural fibers, and which, moreover, will last considerably longer than the brooms used heretofore because of the greater resistance to wear of the materials employed for making the fibers in accordance with my method.

I have found that various of the so-called plastic materials, i. e., the artificial, organic materials which are commonly termed plastic, such as the vinyl resins, the cellulose plastics, polystyrene, etc., may beemployed in accordance with my method to produce the fibers 25. However, polystyrene is preferable when such fibers are to be used for manufacturing such articles as polystyrene, although it will be understood that iit is also generally applicable to other materials.

Polystyrene is a material which becomes sufficiently plastic for use in accordance with the method of my invention at a temperature of approximately 300 F., and which remains sufficiently viscous for use in connection therewith up to a temperature ofapproximately 425 F. It has been my experience that at temperatures below 300 F., the polystyrene becomes too viscous to permit drawing it from the cone 19 at a practical rate and also is difficult to draw without breaking the filament 20. Moreover, at temperatures below 300 the polystyrene is so viscous that the filament 20 is too thick for use as broom straws as will be discussed in more detail hereinafter. At temperatures above approximately 425 l t, the plasticity of the polystyrene increases to such an extent that the cone E9 tends to sag under its own weight and the filament 20 tends to part easily. Moreover, at such high temperatures the filament 20 becomes very fine and must be drawn at an exceedingly high rate as will be pointed out in more detail hereinafter.

I have found that the temperature of the polystyrene in the cylinder i is preferably maintained at a temperature of from 325 F. to 425 F. for best results, the optimum temperature being in the neighborhood of 350 F. As previously mentioned, the temperature of the poly- 6. styrene in the cylinder It may be maintain d at the; desired value by manipul tion o th .0.1 trols for the heating unit I3.

Tests performed in accordance with my method show that the thickness of the filament 20 drawn from the cone I9 is largely determined. by two factors, viz., the temperature of the polystyrene, or other material, and the rate at which the material is drawn from the cone I9. I have found, for example, that a polystyrene filament having an average thickness of 0.070 inch may be obtained by maintaining the. temperature of the. material in the cylinder In at approximate- 13 325" F. and. by drawing the filament at. a rate of approximately 5 linear feet per minute. Thicker filaments may be obtained by maintaining the polystyrene at a lower temperature, but, as previously mentioned, the drawing rate becomes so low as to be impractical for many purposes. I A very thin filament til may e obtained by drawing the polystyrene from the cone {0 at a high rate with the material at a temperature near the upper limit of the preferred range. For example, a filament 20 haying. an avera thickness of approximately 0.010 inch may be obtained by drawing the filament at a rate of approximately 100, linear feet, per minute with the temperature of: he polystyrene in h ylinder [0 at approximately 400 F. Even finerfilaments may be obtained by maintaining the temperature of the polystyrene at, a higher value, but the rate at which the filament must be. drawn increases very rapidly as the temperature is in creased above 400 F. For examplaat a ternperature of approximately 425 the rateof drawing may be increased to more than 200 feet per minute but the resulting filament will be exceedingly fine. Above 425 Fa, it is very difficult to draw polystyrene since its cohesive power is so reduced that the resulting filament may not support its own weight and will tend to break before it has. cooled sufficiently to set.

When the filament 20 is to be severed into fibers 25 for use in the manufacture of such items as whisk brooms, the average thickness of the filament is preferably maintained at approximately 0.035 inch, for example. Such an average thickness may be obtained maintain-= ing the temperature of the polystyrene at approximately 350" and by drawing the filament at a rate of approximately- 20. linear feet per minute. This thickness may also be obtained by drawing the material. at a. higher temperature, e. g., 395 F., but the drawing rate must be reduced to a lower value, c. g., 12 linear feet per minute, to maintain the desired thickness of the filament.

The size and shape of the orifice l1 does not appear to be particularly important so long as the volume of the cone I9 is maintained substantially constant by maintaining the rate at Which material is drawn from the cone and the rate at which additional material is supplied to the cone through the orifice I! substantially equal. More specifically, as long as the size of the cone is maintained substantially constant and as long as the temperature of the polystyrene and the drawing and feeding rates are compatible, the size and shape of the orifice I! represent a relatively negligible factor. When drawing polystyrene at the temperatures and rates mentioned heretofore, I have found that a circular orifice approximately 0.125 inch in diameter is satisfactory, although the diameter of the orifice may be varied somewhat if desired. However, it will be apparent that if the size of the orifice is reduced materially, it will be difiicult to feed the polystyrene or other material through the orifice when it is relatively viscous. On the other hand, if the size of the orifice is increased materially, extremely plastic materials will tend to flow through the orifice at an excessive rate and dilficulty in maintaining the volume of the cone l9 constant may be encountered.

Although I have disclosed two exemplary embodiments of my method and apparatus, and have cited materials and operating conditions suitable for use in connection therewith to illustrate the operation of my invention, it will be understood that the steps of the method, the apparatus, the materials and the operating conditions which I have disclosed may be modified in various respects without necessarily departing from the spirit of the invention. Accordingly, I hereby reserve the right to all such modifications as properly come within the scope of the invention as set forth in the appended claims.

I claim as my invention:

1. A method of forming a drawable material including the steps of maintaining a body of the material substantially in the shape of a cone having its axis intersecting its base at an angle of less than 90; and drawing a filament of the material from the apex of said cone along a path which substantially coincides with an extension of the axis of said cone.

2. A method of forming a drawable material, including the steps of: maintaining a body of the material substantially in the shape of a cone the axis of which intersects its base at an angle of approximatey 45; and drawing a filament of the material from the apex of said cone along a path which substantially coincides with an extension of the axis of said cone.

3. A method of forming a material which, when heated, is rendered. plastic, including the steps of: heating the material to render it plastic; maintaining a body of the plastic material substantially in the shape of a cone the axis of which intersects its base at an angle of less than 90; and drawing a filament of the material from the apex of said cone along a path which is substantially an extension of the axis of said cone.

4. A method of forming a material which is rendered plastic when heated above a predetermined temperature and which sets when cooled below said predetermined temperature, including the steps of heating the material above said predetermined temperature to render it plastic; maintaining a body of the plastic material substantially in the shape of a cone the axis of which intersects the base of the cone at an angle of less than and drawing a filament of the material from the apex of said cone along a path which is substantially an extension of the axis of said cone and at an ambient temperature less than said predetermined temperature, drawing said filament along said path resulting in flattening of said filament.

5. A method of forming polystyrene, including the steps of: heating the polystyrene to a temperature above that at which it begins to become plastic; maintaining a body of the plastic polystyrene substantially in the shape of a cone; continuously drawing a filament of the polystyrene from the apex of said cone at the ambient temperature and along a path which is substantially an extension of the axis of said cone; and flattening the filament by maintaining the axis of said cone at an angle of less than 90 with respect to its base.

6. The method defined in claim 5 wherein said heating step comprises elevating the temperature of the polystyrene to between 325 F. and 425 F.

7. The method defined in claim 5 wherein said heating step comprises elevating the temperature of the polystyrene to between 325 F. and 425 F., and wherein said drawing step comprises drawing said filament from said cone at between 5 and 290 linear feet per minute.

8. A method of forming a drawable material, including the steps of extruding the material; and drawing a filament from the extruded material along a path which makes an acute angle with the direction of extrusion of the material, thereby maintaining the extruded material in the shape of a cone the axis of which makes an angle of less than 90 with its :base and the axis of which is substantially an extension of said path.

BRUNO MONTERO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,944,378 Thenoz Jan. 23, 1934 2,175,125 Mack Oct. 3, 1939 2,212,770 Foster Aug. 27, 1940 2,291,873 Brubaker Aug. 4, 1942 2,369,506 Weibel Feb. 13, 1945 

4. A METHOD OF FORMING A MATERIAL WHICH IS RENDERED PLASTIC WHEN HEATED ABOVE A PREDETERMINED TEMPERATURE AND WHICH SETS WHEN COOLED BELOW SAID PREDETERMINED TEMPERATURE, INCLUDING THE STEPS OF: HEATING THE MATERIAL ABOVE SAID PREDETERMINED TEMPERATURE TO RENDER IT PLASTIC; MAINTAINING A BODY OF THE PLASTIC MATERIAL SUBSTANTIALLY IN THE SHAPE A CONE THEHE AXIS OF WHICH INTERSECTS THE BASE OF THE CONE THE AN ANGLE OF LESS THAN 90*; AND DRAWING A FILAMENT OF THE MATERIAL FROM THE APEX OF SAID CONE ALONG A PATH WHICH IS SUBSTANTIALLY AN EXTENSION OF THE AXIS OF SAID CONE AND AT AN AMBIENT TEMPERATURE LESS THAN SAID PREDETERMINED TEMPERATURE, DRAWING SAID FILAMENT ALONG SAID PATH RESULTING IN FLATTENING OF SAID FILAMENT. 